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Old 31-08-2007, 15:54   #1
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In gear or out when sailing?

ok we were having a chat the other day around the pub if you leave your engine in gear when sailing so as to stop the prop turning. the argument was that if left out of gear and the prop is turning it makes the gears in the box run on the back faces of the gears causing damage. of course some said this was true and some said it was rubbish. Which way do you all sail? In gear or out of gear?
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Old 31-08-2007, 16:26   #2
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sailing in gear or out

it depends on the transmision you have, some are designed for it others aren't.
also if it is hydaulic as a rule unless you have a brake set up you cannot stop the shaft from turning
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Old 31-08-2007, 17:01   #3
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we have a hurth transmission and it recomends putting it in reverse to lock it from spinning
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Old 31-08-2007, 18:08   #4
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It's all about the transmission cooling. Read the transmission docs. based om the advanced studies done by the Navy they say lock the prop. The difference if there is no transmission issues is pointless to argue. You can't go that fast one way or another so long as your transmission is properly cooled. All my boats say lock in reverse with the Mickey Ears up (like you could really check).
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Old 31-08-2007, 19:30   #5
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Having owned one boat and chartering boats for the past three years, I have made it a practice to always sail with the transmission in reverse. I figure if it doesn't need to be in reverse, it certainly want hurt (that,s an engineer's viewpoint anyway ) We owned an Oday 28 at one time and if I forgot to put the transmission in reverse, I would always know because I could actually hear and feel the transmission turning.
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Old 31-08-2007, 19:33   #6
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MD17D with a direct drive - In reverse for sailing.

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Old 31-08-2007, 21:48   #7
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Quote:
Originally Posted by viking69 View Post
ok we were having a chat the other day around the pub if you leave your engine in gear when sailing so as to stop the prop turning. the argument was that if left out of gear and the prop is turning it makes the gears in the box run on the back faces of the gears causing damage. of course some said this was true and some said it was rubbish. Which way do you all sail? In gear or out of gear?
Yo Viking,

in reverse is most common, as it is possible to damage some transmissions. A spinning propeller is presumed to create significantly more drag.

best, andy
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Old 31-08-2007, 22:44   #8
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Our Volvo manual says in reverse. Saildrive.
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Old 01-09-2007, 03:54   #9
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I think if you do a search on here for this issue, you'll find this has been dicussed time and time again. It's a question for which there is no correct answer.

Transmissions which have an independent oil supply may be sailed in neutral. Those which are lubricated from the engine sump, must be locked, usually in reverse. The difference in speed is seldom more than 1/2 knot with one 2 bladed prop in the water.

On my boat it's a a 1 knot difference with two, 2 bladed props.
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Old 01-09-2007, 14:03   #10
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ok thanks all. it would appear that most run with it locked in gear.
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Old 01-09-2007, 17:13   #11
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This is from Yanmarhelp.com......



The gear lever should never be put into ahead to stop the shaft turning. Yanmar recommend that the gear lever is left in neutral as this will not damage the gearbox. If left in astern the clutch cone may jam and will only release once the engine is started. This means you have to start the engine in astern gear. Unfortunately some boats (particually American boats - U.S. Coastguard reg) are fitted with "start in gear protection" this prevents the engine from starting if it is in gear, this would leave you unable to start the engine.
Ideally a shaft brake should be used to prevent the shaft from turning
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Old 01-09-2007, 18:35   #12
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Right... I have twin Yanmars and my manuals say the same thing.

Shaft breaks would save a little wear and tear on the cutlass bearing, but I enjoy sailing fast so my transmissions are both in neutral while sailing. By the way, if you do have Yanmars, it's also the safest per the manual.
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Old 01-09-2007, 19:39   #13
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Rick,

you said you enjoy sailing fast so you leave your transmissions in neutral. If you do an internet search you'll actually find many sources to state that a fixed prop has less drag than a rotating prop. Surprising, but through all my internet research this seems to be the concensus.

Our Yanmar 3QM30F has a Kanzaki KH18 gear box which has a bath type cooling system. Yanmar says it's okay to let it free spin but we use a shaft lock made by Shaftloc, works pretty good.
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Old 01-09-2007, 22:29   #14
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I'm a big fan of folding or feathering props. Had a 3 blade maxprop on my last boat and my current boat has a Gori 2 blade. It's ok but I'm looking...

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Old 02-09-2007, 02:48   #15
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If you do an internet search you'll actually find many sources to state that a fixed prop has less drag than a rotating prop. Surprising, but through all my internet research this seems to be the concensus
This is because a Propellor is a form of a "Rotary Wing". Each blade is a wing and once water flows over it's surface correctly, it creates "lift" just like any wing. If a prop is allowed to free wheel in the water, then it will act in the same way a Helicopter uses Auto rotate to stop it from going into the ground when the engine fails. The drag on the boat is created as the speed of propellor rotation increases. As it increases, more resistance to the rotation is applied by friction from the gearbox. So the propellor becomes drag to the boat, just like the helicopter blade. It is less noticable at slow speeds and greatly increases as speed increases.
If the propellor is locked, then water flows over the blade in the wrong way and the blade "stalls". This has a reverse affect. At low speed, the drag of the stalled propellor is large. At a higher speed, the drag is less noticable to the increased force from the wind.

I won't go into the issue of in/out of gear. As Rick505 said, there has been a lot discussed int he past and a search will reveal much information.
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